PRODUCTION IN THE ANT LEPTOTHORAX-UNIFASCIATUS (HYMENOPTERA, FORMICIDAE)

The methods used so far for estimating production in ant societies are inadequate because elimination (notably mortality) is hardly taken in to account if at all. We present a new method, and apply it to laborat ory societies of the ant Leptothorax unifasciatus (Latreille). Product ion was studied al two levels of integration, those of the individual and the society, which differ in the part of biomass which is recycled or eliminated. Growing societies reared in the laboratory under fluct uating conditions were used for estimating brood production during an annual cycle. All individuals were counted and measured every two week s. Larval survival was estimated from artificial cohorts. By means of a population dynamical model, the larval population was divided into t hree subpopulations, comparable to cohorts, the production of which wa s estimated by the classical ''growth increment summation'' method. To tal larval survival was generally high (83%), but there was a high mor tality in the prepupal and pupal stages so that the overall survival f rom egg to image reached 65%. Losses of biomass during metamorphorsis amounted to 19% of brood production. Recycled biomass and elimination represented 2% and 41%, respectively, of the production at the society level. This suggests that the supposed social advantage of recycling is virtually absent and that neglecting elimination can lead to an und erestimation of production by a factor of 1.7.